Solid Ion Conductor Compound for Lithium Metal Battery Stability

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Solution Overview

Problem

Commercially available solid electrolytes for lithium metal batteries lack stability against lithium metal and have low lithium ion conductivity, and liquid electrolytes pose a fire risk due to flammable organic solvents.

Innovation Solution

A solid ion conductor compound with the composition Li6−wHf2−xMxO7−yZy, where M is a pentavalent or hexavalent cation and Z is an anion, is developed, which includes a method of preparation involving the heat-treatment of lithium, tetravalent, and pentavalent/hexavalent cationic compounds in an oxidizing atmosphere, enhancing lithium ion conductivity and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If commercially available solid electrolyte materials are used, then safety against fire or explosion is improved, but lithium ion conductivity deteriorates (much lower than liquid electrolytes)

Engineering Contradiction:

ImprovesafetyVSAvoidlithium ion conductivity

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent uses composite materials by combining multiple elements (Li, Hf, M, O, Z) to create a new solid electrolyte compound with the formula Li6-wHf2-xMxO7-yZy. This composite approach allows the material to simultaneously achieve high lithium ion conductivity and stability against lithium metal, resolving the contradiction between safety and conductivity performance.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies parameter changes by systematically varying the oxidation states and ratios of different elements in the solid electrolyte compound. By controlling the oxidation number of M (5 or 6) and adjusting the stoichiometric parameters (x, y, z), the material achieves optimized lithium ion conductivity while maintaining structural stability and safety.

Inventive Principle:

Principle #35Parameter changes

2Object-generated harmful factors

If liquid electrolytes are used, then lithium ion conductivity is improved, but fire risk increases due to flammable organic solvents

Engineering Contradiction:

Improvelithium ion conductivityVSAvoidfire risk

Core Design Contradiction:

Object-generated harmful factorsVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the harmful organic solvent component from the electrolyte system entirely, replacing it with an inorganic solid electrolyte compound. This extraction eliminates the fire risk associated with flammable organic solvents while maintaining high lithium ion conductivity through the solid state ion conduction mechanism.

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If solid electrolytes are used to improve safety, then stability against fire or explosion is improved, but stability against lithium metal deteriorates (not sufficiently stable)

Engineering Contradiction:

ImprovesafetyVSAvoidstability against lithium metal

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent applies parameter changes by optimizing the oxidation states and stoichiometric ratios of elements in the solid electrolyte compound. By controlling the oxidation number of M (5 or 6) and adjusting parameters x, y, and z in the formula Li6-wHf2-xMxO7-yZy, the material achieves both safety and sufficient stability against lithium metal.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials combining Li, Hf, M (pentavalent or hexavalent), O, and Z elements to create a solid electrolyte that simultaneously provides safety and stability against lithium metal. The synergistic interaction between these elements resolves the contradiction between safety and compositional stability.

Inventive Principle:

Principle #40Composite materials

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solid ion conductor compound achieves improved lithium ion conductivity and stability against lithium metal, reducing the risk of fire and enhancing safety in lithium batteries.

Implementation Method 1

the lithium ion conductivity of commercially available solid electrolytes is much lower than liquid electrolytes

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Implementation Method 2

heat-treating the mixture in an oxidizing atmosphere to provide a solid ion conductor compound

Methodology Applied

Scientific EffectHeat treatment: Heat Treatment

Data Source

PatentUS11611103B2Solid ion conductor compound, solid electrolyte comprising the same, electrochemical cell comprising the solid ion conductor compound, and preparation method thereof

Publication Date: 2023.03.21 SAMSUNG ELECTRONICS CO LTD

AI summary

A solid ion conductor compound includes a compound represented by Formula 1:Li6−wHf2−xMxO7−yZy Formula 1where, in Formula 1, M is an element having an oxidation number of a and a is 5, 6, or a combination thereof, Z is an element having an oxidation number of −1, and 0<x<2, 0≤y≤2, and 0<w<6 and w=[(a−4)×x]+y.